Apparatus, method, and computer program product for structured waveguide transport using microbubbles

ABSTRACT

An apparatus and method for a transport. The transport including a waveguide including a guiding region and one or more bounding regions for enhancing containment of transmitted radiation within the guiding region, a portion of the waveguide defining a plurality of voids; and a gas disposed in the plurality of voids to enhance an influencer response attribute of the waveguide. A method of operating the transport includes: a) propagating a radiation signal through a waveguide including a guiding region and one or more bounding regions for enhancing containment of transmitted radiation within the guiding region, a portion of the waveguide defining a plurality of voids; and b) enhancing a response of the radiation signal to an influencer applying an influence on the waveguide using a gas disposed in the plurality of voids.

CROSSREF

This application claims benefit of U.S. Provisional Application No.60/544,591 filed 12 Feb. 2004, and is a Continuation-In-Part of each ofthe following U.S. patent application Ser. Nos. 10/812,294, 10/811,782,and 10/812,295 (each filed 29 Mar. 2004); and is a Continuation-In-Partof each of the following U.S. patent application Ser. Nos. 11/011,761,11/011,751, 11/011,496, 11/011,762, and 11/011,770 (each filed 14 Dec.2004); and is a Continuation-In-Part of each of the following U.S.patent application Ser. Nos. 10/906,220, 10/906,221, 10/906,222,10/906,223, 10/906,224, 10/906,226, and 10/906,226 (each filed 9 Feb.2005). The disclosures of which are each incorporated in theirentireties for all purposes.

BACKGROUND

The present invention relates generally to a transport for propagatingradiation, and more specifically to a waveguide having a guiding channelthat includes optically-active constituents that enhance aresponsiveness of a radiation-influencing property of the waveguide toan outside influence.

The Faraday Effect is a phenomenon wherein a plane of polarization oflinearly polarized light rotates when the light is propagated through atransparent medium placed in a magnetic field and in parallel with themagnetic field. An effectiveness of the magnitude of polarizationrotation varies with the strength of the magnetic field, the Verdetconstant inherent to the medium and the light path length. The empiricalangle of rotation is given byβ=VBd,  (Eq. 1)

-   -   where V is called the Verdet constant (and has units of arc        minutes cm−1 Gauss−1), B is the magnetic field and d is the        propagation distance subject to the field. In the quantum        mechanical description, Faraday rotation occurs because        imposition of a magnetic field alters the energy levels.

It is known to use discrete materials (e.g., iron-containing garnetcrystals) having a high Verdet constant for measurement of magneticfields (such as those caused by electric current as a way of evaluatingthe strength of the current) or as a Faraday rotator used in an opticalisolator. An optical isolator includes a Faraday rotator to rotate by45° the plane of polarization, a magnet for application of magneticfield, a polarizer, and an analyzer. Conventional optical isolators havebeen of the bulk type wherein no waveguide (e.g., optical fiber) isused.

In conventional optics, magneto-optical modulators have been producedfrom discrete crystals containing paramagnetic and ferromagneticmaterials, particularly garnets (yttrium/iron garnet for example).Devices such as these require considerable magnetic control fields. Themagneto-optical effects are also used in thin-layer technology,particularly for producing non-reciprocal devices, such asnon-reciprocal junctions. Devices such as these are based on aconversion of modes by Faraday Effect or by Cotton-Moutton effect.

A further drawback to using paramagnetic and ferromagnetic materials inmagneto-optic devices is that these materials may adversely affectproperties of the radiation other than polarization angle, such as forexample amplitude, phase, and/or frequency.

The prior art has known the use of discrete magneto-optical bulk devices(e.g., crystals) for collectively defining a display device. These priorart displays have several drawbacks, including a relatively high costper picture element (pixel), high operating costs for controllingindividual pixels, increasing control complexity that does not scalewell for relatively large display devices.

Conventional imaging systems may be roughly divided into two categories:(a) flat panel displays (FPDs), and (b) projection systems (whichinclude cathode ray tubes (CRTs) as emissive displays). Generallyspeaking, the dominant technologies for the two types of systems are notthe same, although there are exceptions. These two categories havedistinct challenges for any prospective technology, and existingtechnologies have yet to satisfactorily conquer these challenges.

A main challenge confronting existing FPD technology is cost, ascompared with the dominant cathode ray tube (CRT) technology (“flatpanel” means “flat” or “thin” compared to a CRT display, whose standarddepth is nearly equal to the width of the display area).

To achieve a given set of imaging standards, including resolution,brightness, and contrast, FPD technology is roughly three to four timesmore expensive than CRT technology. However, the bulkiness and weight ofCRT technology, particularly as a display area is scaled larger, is amajor drawback. Quests for a thin display have driven the development ofa number of technologies in the FPD arena.

High costs of FPD are largely due to the use of delicate componentmaterials in the dominant liquid crystal diode (LCD) technology, or inthe less-prevalent gas plasma technology. Irregularities in the nematicmaterials used in LCDs result in relatively high defect rates; an arrayof LCD elements in which an individual cell is defective often resultsin the rejection of an entire display, or a costly substitution of thedefective element.

For both LCD and gas-plasma display technology, the inherent difficultyof controlling liquids or gasses in the manufacturing of such displaysis a fundamental technical and cost limitation.

An additional source of high cost is the demand for relatively highswitching voltages at each light valve/emission element in the existingtechnologies. Whether for rotating the nematic materials of an LCDdisplay, which in turn changes a polarization of light transmittedthrough the liquid cell, or excitation of gas cells in a gas plasmadisplay, relatively high voltages are required to achieve rapidswitching speeds at the imaging element. For LCDs, an “active matrix,”in which individual transistor elements are assigned to each imaginglocation, is a high-cost solution.

As image quality standards increase, for high-definition television(HDTV) or beyond, existing FPD technologies cannot now deliver imagequality at a cost that is competitive with CRT's. The cost differentialat this end of the quality range is most pronounced. And delivering 35mm film-quality resolution, while technically feasible, is expected toentail a cost that puts it out of the realm of consumer electronics,whether for televisions or computer displays.

For projection systems, there are two basic subclasses: television (orcomputer) displays, and theatrical motion picture projection systems.Relative cost is a major issue in the context of competition withtraditional 35 mm film projection equipment. However, for HDTV,projection systems represent the low-cost solution, when comparedagainst conventional CRTs, LCD FPDs, or gas-plasma FPDs.

Current projection system technologies face other challenges. HDTVprojection systems face the dual challenge of minimizing a depth of thedisplay, while maintaining uniform image quality within the constraintsof a relatively short throw-distance to the display surface. Thisbalancing typically results in a less-than-satisfactory compromise atthe price of relatively lower cost.

A technically-demanding frontier for projection systems, however, is inthe domain of the movie theater. Motion-picture screen installations arean emerging application area for projection systems, and in thisapplication, issues regarding console depth versus uniform image qualitytypically do not apply. Instead, the challenge is in equaling (atminimum) the quality of traditional 35 mm film projectors, at acompetitive cost. Existing technologies, including direct Drive ImageLight Amplifier (“D-ILA”), digital light processing (“DLP”), andgrating-light-valve (“GLV”)-based systems, while recently equaling thequality of traditional film projection equipment, have significant costdisparities as compared to traditional film projectors.

Direct Drive Image Light Amplifier is a reflective liquid crystal lightvalve device developed by JVC Projectors. A driving integrated circuit(“IC”) writes an image directly onto a CMOS based light valve. Liquidcrystals change the reflectivity in proportion to a signal level. Thesevertically aligned (homeoptropic) crystals achieve very fast responsetimes with a rise plus fall time less than 16 milliseconds. Light from axenon or ultra high performance (“UHP”) metal halide lamp travelsthrough a polarized beam splitter, reflects off the D-ILA device, and isprojected onto a screen.

At the heart of a DLP™ projection system is an optical semiconductorknown as a Digital Micromirror Device, or DMD chip, which was pioneeredby Dr. Larry Hornbeck of Texas Instruments in 1987. The DMD chip is asophisticated light switch. It contains a rectangular array of up to 1.3million hinge-mounted microscopic mirrors; each of these micromirrorsmeasures less than one-fifth the width of a human hair, and correspondsto one pixel in a projected image. When a DMD chip is coordinated with adigital video or graphic signal, a light source, and a projection lens,its mirrors reflect an all-digital image onto a screen or other surface.The DMD and the sophisticated electronics that surround it are calledDigital Light Processing™ technology.

A process called GLV (Grating-Light-Valve) is being developed. Aprototype device based on the technology achieved a contrast ratio of3000:1 (typical high-end projection displays today achieve only 1000:1).The device uses three lasers chosen at specific wavelengths to delivercolor. The three lasers are: red (642 nm), green (532 nm), and blue (457nm). The process uses MEMS technology (MicroElectroMechanical) andconsists of a microribbon array of 1,080 pixels on a line. Each pixelconsists of six ribbons, three fixed and three which move up/down. Whenelectrical energy is applied, the three mobile ribbons form a kind ofdiffraction grating which “filters” out light.

Part of the cost disparity is due to the inherent difficulties thosetechnologies face in achieving certain key image quality parameters at alow cost. Contrast, particularly in quality of “black,” is difficult toachieve for micro-mirror DLP. GLV, while not facing this difficulty(achieving a pixel nullity, or black, through optical grating waveinterference), instead faces the difficulty of achieving an effectivelyfilm-like intermittent image with a line-array scan source.

Existing technologies, either LCD or MEMS-based, are also constrained bythe economics of producing devices with at least 1 K×1 K arrays ofelements (micro-mirrors, liquid crystal on silicon (“LCoS”), and thelike). Defect rates are high in the chip-based systems when involvingthese numbers of elements, operating at the required technicalstandards.

It is known to use stepped-index optical fibers in cooperation with theFaraday Effect for various telecommunications uses. Thetelecommunications application of optical fibers is well-known, howeverthere is an inherent conflict in applying the Faraday Effect to opticalfibers because the telecommunications properties of conventional opticalfibers relating to dispersion and other performance metrics are notoptimized for, and in some cases are degraded by, optimizations for theFaraday Effect. In some conventional optical fiber applications,ninety-degree polarization rotation is achieved by application of a onehundred Oersted magnetic field over a path length of fifty-four meters.Placing the fiber inside a solenoid and creating the desired magneticfield by directing current through the solenoid applies the desiredfield. For telecommunications uses, the fifty-four meter path length isacceptable when considering that it is designed for use in systemshaving a total path length measured in kilometers.

Another conventional use for the Faraday Effect in the context ofoptical fibers is as a system to overlay a low-rate data transmission ontop of conventional high-speed transmission of data through the fiber.The Faraday Effect is used to slowly modulate the high-speed data toprovide out-of-band signaling or control. Again, this use is implementedwith the telecommunications use as the predominate consideration.

In these conventional applications, the fiber is designed fortelecommunications usage and any modification of the fiber propertiesfor participation in the Faraday Effect is not permitted to degrade thetelecommunications properties that typically include attenuation anddispersion performance metrics for kilometer+−length fiber channels.

Once acceptable levels were achieved for the performance metrics ofoptical fibers to permit use in telecommunications, optical fibermanufacturing techniques were developed and refined to permit efficientand cost-effective manufacturing of extremely long-lengths of opticallypure and uniform fibers. A high-level overview of the basicmanufacturing process for optical fibers includes manufacture of aperform glass cylinder, drawing fibers from the preform, and testing thefibers. Typically a perform blank is made using a modified chemicalvapor deposition (MCVD) process that bubbles oxygen through siliconsolutions having a requisite chemical composition necessary to producethe desired attributes (e.g., index of refraction, coefficient ofexpansion, melting point, etc.) of the final fiber. The gas vapors areconducted to an inside of a synthetic silica or quartz tube (cladding)in a special lathe. The lathe is turned and a torch moves along anoutside of the tube. Heat from the torch causes the chemicals in thegases to react with oxygen and form silicon dioxide and germaniumdioxide and these dioxides deposit on the inside of the tube and fusetogether to form glass. The conclusion of this process produces theblank preform.

After the blank preform is made, cooled, and tested, it is placed insidea fiber drawing tower having the preform at a top near a graphitefurnace. The furnace melts a tip of the preform resulting in a molten“glob” that begins to fall due to gravity. As it falls, it cools andforms a strand of glass. This strand is threaded through a series ofprocessing stations for applying desired coatings and curing thecoatings and attached to a tractor that pulls the strand at acomputer-monitored rate so that the strand has the desired thickness.Fibers are pulled at about a rate of thirty-three to sixty-sixfeet/second with the drawn strand wound onto a spool. It is not uncommonfor these spools to contain more than one point four (1.4) miles ofoptical fiber.

This finished fiber is tested, including tests for the performancemetrics. These performance metrics for telecommunications grade fibersinclude: tensile strength (100,000 pounds per square inch or greater),refractive index profile (numerical aperture and screen for opticaldefects), fiber geometry (core diameter, cladding dimensions and coatingdiameters), attenuation (degradation of light of various wavelengthsover distance), bandwidth, chromatic dispersion, operatingtemperature/range, temperature dependence on attenuation, and ability toconduct light underwater.

In 1996, a variation of the above-described optical fibers wasdemonstrated that has since been termed photonic crystal fibers (PCFs).A PCF is an optical fiber/waveguiding structure that uses amicrostructured arrangement of low-index material in a backgroundmaterial of higher refractive index. The background material is oftenundoped silica and the low index region is typically provided by airvoids running along the length of the fiber. PCFs are divided into twogeneral categories: (1) high index guiding fibers, and (2) low indexguiding fibers.

Similar to conventional optic fibers described previously, high indexguiding fibers are guiding light in a solid core by the Modified TotalInternal Reflection (MTIR) principle. Total internal reflection iscaused by the lower effective index in the microstructured air-filledregion.

Low index guiding fibers guide light using a photonic bandgap (PBG)effect. Light is confined to the low index core as the PBG effect makespropagation in the microstructured cladding region impossible.

While the term “conventional waveguide structure” is used to include thewide range of waveguiding structures and methods, the range of thesestructures may be modified as described herein to implement embodimentsof the present invention. The characteristics of different fiber typesaides are adapted for the many different applications for which they areused. Operating a fiber optic system properly relies on knowing whattype of fiber is being used and why.

Conventional systems include single-mode, multimode, and PCF waveguides,and also include many sub-varieties as well. For example, multimodefibers include step-index and graded-index fibers, and single-modefibers include step-index, matched clad, depressed clad and other exoticstructures. Multimode fiber is best designed for shorter transmissiondistances, and is suited for use in LAN systems and video surveillance.Single-mode fibers are best designed for longer transmission distances,making it suitable for long-distance telephony and multichanneltelevision broadcast systems. “Air-clad” or evanescently-coupledwaveguides include optical wire and optical nano-wire.

Stepped-index generally refers to provision of an abrupt change of anindex of refraction for the waveguide—a core has an index of refractiongreater than that of a cladding. Graded-index refers to structuresproviding a refractive index profile that gradually decreases fartherfrom a center of the core (for example the core has a parabolicprofile). Single-mode fibers have developed many different profilestailored for particular applications (e.g., length and radiationfrequency(ies) such as non dispersion-shifted fiber (NDSF),dispersion-shifted fiber (DSF) and non-zero-dispersion-shifted fiber(NZ-DSF)). An important variety of single-mode fiber has been developedreferred to as polarization-maintaining (PM) fiber. All othersingle-mode fibers discussed so far have been capable of carryingrandomly polarized light. PM fiber is designed to propagate only onepolarization of the input light. PM fiber contains a feature not seen inother fiber types. Besides the core, there are additional (2)longitudinal regions called stress rods. As their name implies, thesestress rods create stress in the core of the fiber such that thetransmission of only one polarization plane of light is favored.

As discussed above, conventional magneto-optical systems, particularlyFaraday rotators and isolators, have employed special magneto-opticalmaterials that include rare earth doped garnet crystals and otherspecialty materials, commonly an yttrium-iron-garnet (YIG) or abismuth-substituted YIG. A YIG single crystal is grown using a floatingzone (FZ) method. In this method, Y₂O₃ and Fe₂O₃ are mixed to suit thestoichiometric composition of YIG, and then the mixture is sintered. Theresultant sinter is set as a mother stick on one shaft in an FZ furnace,while a YIG seed crystal is set on the remaining shaft. The sinteredmaterial of a prescribed formulation is placed in the central areabetween the mother stick and the seed crystal in order to create thefluid needed to promote the deposition of YIG single crystal. Light fromhalogen lamps is focused on the central area, while the two shafts arerotated. The central area, when heated in an oxygenic atmosphere, formsa molten zone. Under this condition, the mother stick and the seed aremoved at a constant speed and result in the movement of the molten zonealong the mother stick, thus growing single crystals from the YIGsinter.

Since the FZ method grows crystal from a mother stick that is suspendedin the air, contamination is precluded and a high-purity crystal iscultivated. The FZ method produces ingots measuring 012×120 mm.

Bi-substituted iron garnet thick films are grown by a liquid phaseepitaxy (LPE) method that includes an LPE furnace. Crystal materials anda PbO—B₂O₃ flux are heated and made molten in a platinum crucible.Single crystal wafers, such as (GdCa)₂(GaMgZr)₅O₁₂, are soaked on themolten surface while rotated, which causes a Bi-substituted iron garnetthick film to be grown on the wafers. Thick films measuring as much as 3inches in diameter can be grown.

To obtain 45° Faraday rotators, these films are ground to a certainthickness, applied with anti-reflective coating, and then cut into 1-2mm squares to fit the isolators. Having a greater Faraday rotationcapacity than YIG single crystals, Bi-substituted iron garnet thickfilms must be thinned in the order of 100 μm, so higher-precisionprocessing is required.

Newer systems provide for the production and synthesis ofBismuth-substituted yttrium-iron-garnet (Bi—YIG) materials, thin-filmsand nanopowders. nGimat Co., at 5313 Peachtree Industrial Boulevard,Atlanta, Ga. 30341 uses a combustion chemical vapor deposition (CCVD)system for production of thin film coatings. In the CCVD process,precursors, which are the metal-bearing chemicals used to coat anobject, are dissolved in a solution that typically is a combustiblefuel. This solution is atomized to form microscopic droplets by means ofa special nozzle. An oxygen stream then carries these droplets to aflame where they are combusted. A substrate (a material being coated) iscoated by simply drawing it in front of the flame. Heat from the flameprovides energy that is required to vaporize the droplets and for theprecursors to react and deposit (condense) on the substrate.

Additionally, epitaxial liftoff has been used for achievingheterogeneous integration of many III-V and elemental semiconductorsystems. However, it has been difficult using some processes tointegrate devices of many other important material systems. A goodexample of this problem has been the integration of single-crystaltransition metal oxides on semiconductor platforms, a system needed foron-chip thin film optical isolators. An implementation of epitaxialliftoff in magnetic garnets has been reported. Deep ion implantation isused to create a buried sacrificial layer in single-crystal yttrium irongarnet (YIG) and bismuth-substituted YIG (Bi—YIG) epitaxial layers grownon gadolinium gallium garnet (GGG). The damage generated by theimplantation induces a large etch selectivity between the sacrificiallayer and the rest of the garnet. Ten-micron-thick films have beenlifted off from the original GGG substrates by etching in phosphoricacid. Millimeter-size pieces have been transferred to the silicon andgallium arsenide substrates.

Further, researchers have reported a multilayer structure they call amagneto-optical photonic crystal that displays one hundred forty percent(140%) greater Faraday rotation at 748 nm than a single-layer bismuthiron garnet film of the same thickness. Current Faraday rotators aregenerally single crystals or epitaxial films. The single-crystaldevices, however, are rather large, making their use in applicationssuch as integrated optics difficult. And even the films displaythicknesses on the order of 500 μm, so alternative material systems aredesirable. The use of stacked films of iron garnets, specificallybismuth and yttrium iron garnets has been investigated. Designed for usewith 750-nm light, a stack featured four heteroepitaxial layers of81-nm-thick yttrium iron garnet (YIG) atop 70-nm-thick bismuth irongarnet (BIG), a 279-nm-thick central layer of BIG, and four layers ofBIG atop YIG. To fabricate the stack, a pulsed laser deposition using anLPX305i 248-nm KrF excimer laser was used.

As seen from the discussion above, the prior art employs specialtymagneto-optic materials in most magneto-optic systems, but it has alsobeen known to employ the Faraday Effect with less traditionalmagneto-optic materials such as the non-PCF optical fibers by creatingthe necessary magnetic field strength—as long as the telecommunicationsmetrics are not compromised. In some cases, post-manufacturing methodsare used in conjunction with pre-made optical fibers to provide certainspecialty coatings for use in certain magneto-optical applications. Thesame is true for specialty magneto-optical crystals and other bulkimplementations in that post-manufacture processing of the premadematerial is sometimes necessary to achieve various desired results. Suchextra processing increases the final cost of the special fiber andintroduces additional situations in which the fiber may fail to meetspecifications. Since many magneto-applications typically include asmall number (typically one or two) of magneto-optical components, therelatively high cost per unit is tolerable. However, as the number ofdesired magneto-optical components increases, the final costs (in termsof dollars and time) are magnified and in applications using hundreds orthousands of such components, it is imperative to greatly reduce unitcost.

What is needed is an alternative waveguide technology that offersadvantages over the prior art to enhance a responsiveness of aradiation-influencing property of the waveguide to an outside influencewhile reducing unit cost and increasing manufacturability,reproducibility, uniformity, and reliability.

BRIEFSUMM

Disclosed is an apparatus and method for a transport. The transportincluding a waveguide including a guiding region and one or morebounding regions for enhancing containment of transmitted radiationwithin the guiding region, a portion of the waveguide defining aplurality of voids; and a gas disposed in the plurality of voids toenhance an influencer response attribute of the waveguide. A method ofoperating the transport includes: a) propagating a radiation signalthrough a waveguide including a guiding region and one or more boundingregions for enhancing containment of transmitted radiation within theguiding region, a portion of the waveguide defining a plurality ofvoids; and b) enhancing a response of the radiation signal to aninfluencer applying an influence on the waveguide using a gas disposedin the plurality of voids.

It is also a preferred embodiment of the present invention for atransport manufacturing method, the method including: a) forming awaveguide having a guiding region and one or more bounding regions forenhancing containment of transmitted radiation within the guidingregion, a portion of the waveguide defining a plurality of voids; and b)disposing a gas in the plurality of voids to enhance an influencerresponse attribute of the waveguide.

The apparatus, method, computer program product and propagated signal ofthe present invention provide an advantage of using modified and maturewaveguide manufacturing processes. In a preferred embodiment, thewaveguide is an optical transport, preferably an optical fiber orwaveguide channel adapted to enhance short-length property influencingcharacteristics of the influencer by including optically-activeconstituents while preserving desired attributes of the radiation. In apreferred embodiment, the property of the radiation to be influencedincludes a polarization state of the radiation and the influencer uses aFaraday Effect to control a polarization rotation angle using acontrollable, variable magnetic field propagated parallel to atransmission axis of the optical transport. The optical transport isconstructed to enable the polarization to be controlled quickly usinglow magnetic field strength over very short optical paths. Radiation isinitially controlled to produce a wave component having one particularpolarization; the polarization of that wave component is influenced sothat a second polarizing filter modulates an amplitude of emittedradiation in response to the influencing effect. In the preferredembodiment, this modulation includes extinguishing the emittedradiation. The incorporated patent applications, the priorityapplications and related-applications, disclose Faraday structuredwaveguides, Faraday structured waveguide modulators, displays and otherwaveguide structures and methods that are cooperative with the presentinvention.

Leveraging the mature and efficient fiber optic waveguide manufacturingprocess as disclosed herein as part of the present invention for use inproduction of low-cost, uniform, efficient magneto-optic system elementsprovides an alternative waveguide technology that offers advantages overthe prior art to enhance a responsiveness of a radiation-influencingproperty of the waveguide to an outside influence while reducing unitcost and increasing manufacturability, reproducibility, uniformity, andreliability.

DESCDRAWINGS

FIG. 1 is a general schematic plan view of a preferred embodiment of thepresent invention;

FIG. 2 is a detailed schematic plan view of a specific implementation ofthe preferred embodiment shown in FIG. 1;

FIG. 3 is an end view of the preferred embodiment shown in FIG. 2;

FIG. 4 is a schematic block diagram of a preferred embodiment for adisplay assembly;

FIG. 5 is a view of one arrangement for output ports of the front panelshown in FIG. 4;

FIG. 6 is a schematic representation of a preferred embodiment of thepresent invention for a portion of the structured waveguide shown inFIG. 2;

FIG. 7 is a schematic block diagram of a representative waveguidemanufacturing system for making a preferred embodiment of a waveguidepreform of the present invention; and

FIG. 8 is a schematic diagram of a representative fiber drawing systemfor making a preferred embodiment of the present invention.

DETAILEDDESC

The present invention relates to an alternative waveguide technologythat offers advantages over the prior art to enhance a responsiveness ofa radiation-influencing property of the waveguide to an outsideinfluence while reducing unit cost and increasing manufacturability,reproducibility, uniformity, and reliability. The following descriptionis presented to enable one of ordinary skill in the art to make and usethe invention and is provided in the context of a patent application andits requirements. Various modifications to the preferred embodiment andthe generic principles and features described herein will be readilyapparent to those skilled in the art. Thus, the present invention is notintended to be limited to the embodiment shown but is to be accorded thewidest scope consistent with the principles and features describedherein.

In the following description, three terms have particular meaning in thecontext of the present invention: (1) optical transport, (2) propertyinfluencer, and (3) extinguishing. For purposes of the presentinvention, an optical transport is a waveguide particularly adapted toenhance the property influencing characteristics of the influencer whilepreserving desired attributes of the radiation. In a preferredembodiment, the property of the radiation to be influenced includes itspolarization rotation state and the influencer uses a Faraday Effect tocontrol the polarization angle using a controllable, variable magneticfield propagated parallel to a transmission axis of the opticaltransport. The optical transport is constructed to enable thepolarization to be controlled quickly using low magnetic field strengthover very short optical paths. In some particular implementations, theoptical transport includes optical fibers exhibiting high Verdetconstants for the wavelengths of the transmitted radiation whileconcurrently preserving the waveguiding attributes of the fiber andotherwise providing for efficient construction of, and cooperativeaffectation of the radiation property(ies), by the property influencer.

The property influencer is a structure for implementing the propertycontrol of the radiation transmitted by the optical transport. In thepreferred embodiment, the property influencer is operatively coupled tothe optical transport, which in one implementation for an opticaltransport formed by an optical fiber having a core and one or morecladding layers, preferably the influencer is integrated into or on oneor more of the cladding layers without significantly adversely alteringthe waveguiding attributes of the optical transport. In the preferredembodiment using the polarization property of transmitted radiation, thepreferred implementation of the property influencer is a polarizationinfluencing structure, such as a coil, coilform, or other structurecapable of integration that supports/produces a Faraday Effectmanifesting field in the optical transport (and thus affects thetransmitted radiation) using one or more magnetic fields (one or more ofwhich are controllable).

The structured waveguide of the present invention may serve in someembodiments as a transport in a modulator that controls an amplitude ofpropagated radiation. The radiation emitted by the modulator will have amaximum radiation amplitude and a minimum radiation amplitude,controlled by the interaction of the property influencer on the opticaltransport. Extinguishing simply refers to the minimum radiationamplitude being at a sufficiently low level (as appropriate for theparticular embodiment) to be characterized as “off” or “dark” or otherclassification indicating an absence of radiation. In other words, insome applications a sufficiently low but detectable/discernableradiation amplitude may properly be identified as “extinguished” whenthat level meets the parameters for the implementation or embodiment.The present invention improves the response of the waveguide to theinfluencer by use of optically active constituents disposed in theguiding region during waveguide manufacture.

FIG. 1 is a general schematic plan view of a preferred embodiment of thepresent invention for a Faraday structured waveguide modulator 100.Modulator 100 includes an optical transport 105, a property influencer110 operatively coupled to transport 105, a first property element 120,and a second property element 125.

Transport 105 may be implemented based upon many well-known opticalwaveguide structures of the art. For example, transport 105 may be aspecially adapted optical fiber (conventional or PCF) having a guidingchannel including a guiding region and one or more bounding regions(e.g., a core and one or more cladding layers for the core), ortransport 105 may be a waveguide channel of a bulk device or substratehaving one or more such guiding channels. A conventional waveguidestructure is modified based upon the type of radiation property to beinfluenced and the nature of influencer 110.

Influencer 110 is a structure for manifesting property influence(directly or indirectly such as through the disclosed effects) on theradiation transmitted through transport 105 and/or on transport 105.Many different types of radiation properties may be influenced, and inmany cases a particular structure used for influencing any givenproperty may vary from implementation to implementation. In thepreferred embodiment, properties that may be used in turn to control anoutput amplitude of the radiation are desirable properties forinfluence. For example, radiation polarization angle is one propertythat may be influenced and is a property that may be used to control atransmitted amplitude of the radiation. Use of another element, such asa fixed polarizer will control radiation amplitude based upon thepolarization angle of the radiation compared to the transmission axis ofthe polarizer. Controlling the polarization angle varies the transmittedradiation in this example.

However, it is understood that other types of properties may beinfluenced as well and may be used to control output amplitude, such asfor example, radiation phase or radiation frequency. Typically, otherelements are used with modulator 100 to control output amplitude basedupon the nature of the property and the type and degree of the influenceon the property. In some embodiments another characteristic of theradiation may be desirably controlled rather than output amplitude,which may require that a radiation property other than those identifiedbe controlled, or that the property may need to be controlleddifferently to achieve the desired control over the desired attribute.

A Faraday Effect is but one example of one way of achieving polarizationcontrol within transport 105. A preferred embodiment of influencer 110for Faraday polarization rotation influence uses a combination ofvariable and fixed magnetic fields proximate to or integrated within/ontransport 105. These magnetic fields are desirably generated so that acontrolling magnetic field is oriented parallel to a propagationdirection of radiation transmitted through transport 105. Properlycontrolling the direction and magnitude of the magnetic field relativeto the transport achieves a desired degree of influence on the radiationpolarization angle.

It is preferable in this particular example that transport 105 beconstructed to improve/maximize the “influencibility” of the selectedproperty by influencer 110. For the polarization rotation property usinga Faraday Effect, transport 105 is doped, formed, processed, and/ortreated to increase/maximize the Verdet constant. The greater the Verdetconstant, the easier influencer 110 is able to influence thepolarization rotation angle at a given field strength and transportlength. In the preferred embodiment of this implementation, attention tothe Verdet constant is the primary task with otherfeatures/attributes/characteristics of the waveguide aspect of transport105 secondary. In the preferred embodiment, influencer 110 is integratedor otherwise “strongly associated” with transport 105 through thewaveguide manufacturing process (e.g., the preform fabrication and/ordrawing process), though some implementations may provide otherwise.

Element 120 and element 125 are property elements forselecting/filtering/operating on the desired radiation property to beinfluenced by influencer 110. Element 120 may be a filter to be used asa “gating” element to pass wave components of the input radiation havinga desired state for the appropriate property, or it may be a“processing” element to conform one or more wave components of the inputradiation to a desired state for the appropriate property. Thegated/processed wave components from element 120 are provided to opticaltransport 105 and property influencer 110 controllably influences thetransported wave components as described above.

Element 125 is a cooperative structure to element 120 and operates onthe influenced wave components. Element 125 is a structure that passesWAVE_OUT and controls an amplitude of WAVE_OUT based upon a state of theproperty of the wave component. The nature and particulars of thatcontrol relate to the influenced property and the state of the propertyfrom element 120 and the specifics of how that initial state has beeninfluenced by influencer 110.

For example, when the property to be influenced is a polarizationproperty/polarization rotation angle of the wave components, element 120and element 125 may be polarization filters. Element 120 selects onespecific type of polarization for the wave component, for example righthand circular polarization. Influencer 110 controls a polarizationrotation angle of radiation as it passes through transport 105. Element125 filters the influenced wave component based upon the finalpolarization rotation angle as compared to a transmission angle ofelement 125. In other words, when the polarization rotation angle of theinfluenced wave component matches the transmission axis of element 125,WAVE_OUT has a high amplitude. When the polarization rotation angle ofthe influenced wave component is “crossed” with the transmission axis ofelement 125, WAVE_OUT has a low amplitude. A cross in this contextrefers to a rotation angle about ninety degrees misaligned with thetransmission axis for conventional polarization filters.

Further, it is possible to establish the relative orientations ofelement 120 and element 125 so that a default condition results in amaximum amplitude of WAVE_OUT, a minimum amplitude of WAVE_OUT, or somevalue in between. A default condition refers to a magnitude of theoutput amplitude without influence from influencer 110. For example, bysetting the transmission axis of element 125 at a ninety degreerelationship to a transmission axis of element 120, the defaultcondition would be a minimum amplitude for the preferred embodiment.

Element 120 and element 125 may be discrete components or one or bothstructures may be integrated onto or into transport 105. In some cases,the elements may be localized at an “input” and an “output” of transport105 as in the preferred embodiment, while in other embodiments theseelements may be distributed in particular regions of transport 105 orthroughout transport 105.

In operation, radiation (shown as WAVE_IN) is incident to element 120and an appropriate property (e.g., a right hand circular polarization(RCP) rotation component) is gated/processed to pass an RCP wavecomponent to transport 105. Transport 105 transmits the RCP wavecomponent until it is interacted with by element 125 and the wavecomponent (shown as WAVE_OUT) is passed. Incident WAVE_IN typically hasmultiple orthogonal states to the polarization property (e.g., righthand circular polarization (RCP) and left hand circular polarization(LCP)). Element 120 produces a particular state for the polarizationrotation property (e.g., passes one of the orthogonal states andblocks/shifts the other so only one state is passed). Influencer 110, inresponse to a control signal, influences that particular polarizationrotation of the passed wave component and may change it as specified bythe control signal. Influencer 110 of the preferred embodiment is ableto influence the polarization rotation property over a range of aboutninety degrees. Element 125 then interacts with the wave component as ithas been influenced permitting the radiation amplitude of WAVE_IN to bemodulated from a maximum value when the wave component polarizationrotation matches the transmission axis of element 125 and a minimumvalue when the wave component polarization is “crossed” with thetransmission axis. By use of element 120, the amplitude of WAVE_OUT ofthe preferred embodiment is variable from a maximum level to anextinguished level.

FIG. 2 is a detailed schematic plan view of a specific implementation ofthe preferred embodiment shown in FIG. 1. This implementation isdescribed specifically to simplify the discussion, though the inventionis not limited to this particular example. Faraday structured waveguidemodulator 100 shown in FIG. 1 is a Faraday optical modulator 200 shownin FIG. 2.

Modulator 200 includes a core 205, a first cladding layer 210, a secondcladding layer 215, a coil or coilform 220 (coil 220 having a firstcontrol node 225 and a second control node 230), an input element 235,and an output element 240. FIG. 3 is a sectional view of the preferredembodiment shown in FIG. 2 taken between element 235 and element 240with like numerals showing the same or corresponding structures.

Core 205 may contain one or more of the following dopants added bystandard fiber manufacturing techniques, e.g., variants on the vacuumdeposition method: (a) color dye dopant (makes modulator 200 effectivelya color filter alight from a source illumination system), and (b) anoptically-active dopant, such as YIG/Bi—YIG or Tb or TGG or other dopantfor increasing the Verdet constant of core 205 to achieve efficientFaraday rotation in the presence of an activating magnetic field.Heating or applying stress to the fiber during manufacturing adds holesor irregularities in core 205 to further increase the Verdet constantand/or implement non-linear effects. To simplify the discussion herein,the discussion focuses predominately on non-PCF waveguides. However, inthe context of this discussion, PCF variants may be substituted for thenon-PCF wavelength embodiments unless the context clearly is contrary tosuch substitution. For PCF waveguides, rather than use color dyedopants, color filtering is implemented using wavelength-selectivebandgap coupling or longitudinal structures/voids may be filled anddoped. Therefore, whenever color filtering/dye-doping is discussed inconnection with non-PCF waveguides, the use of wavelength-selectivebandgap coupling and/or filling and doping for PCF waveguides may alsobe substituted when appropriate.

Much silica optical fiber is manufactured with high levels of dopantsrelative to the silica percentage (this level may be as high as fiftypercent dopants). Current dopant concentrations in silica structures ofother kinds of fiber achieve about ninety-degree rotation in a distanceof tens of microns. Conventional fiber manufacturers continue to achieveimprovements in increasing dopant concentration (e.g., fiberscommercially available from JDS Uniphase) and in controlling dopantprofile (e.g., fibers commercially available from Corning Incorporated).Core 205 achieves sufficiently high and controlled concentrations ofoptically active dopants to provide requisite quick rotation with lowpower in micron-scale distances, with these power/distance valuescontinuing to decrease as further improvements are made.

First cladding layer 210 (optional in the preferred embodiment) is dopedwith ferro-magnetic single-molecule magnets, which become permanentlymagnetized when exposed to a strong magnetic field. Magnetization offirst cladding layer 210 may take place prior to the addition to core205 or pre-form, or after modulator 200 (complete with core, cladding,coating(s) and/or elements) is drawn. During this process, either thepreform or the drawn fiber passes through a strong permanent magnetfield ninety degrees offset from a transmission axis of core 205. In thepreferred embodiment, this magnetization is achieved by anelectro-magnetic disposed as an element of a fiber pulling apparatus.First cladding layer 210 (with permanent magnetic properties) isprovided to saturate the magnetic domains of the optically-active core205, but does not change the angle of rotation of the radiation passingthrough fiber 200, since the direction of the magnetic field from layer210 is at right-angles to the direction of propagation. The incorporatedprovisional application describes a method to optimize an orientation ofa doped ferromagnetic cladding by pulverization of non-optimal nuclei ina crystalline structure.

As single-molecule magnets (SMMs) are discovered that may be magnetizedat relative high temperatures, the use of these SMMs will be preferableas dopants. The use of these SMMs allow for production of superiordoping concentrations and dopant profile control. Examples ofcommercially available single-molecule magnets and methods are availablefrom ZettaCore, Inc. of Denver, Colo.

Second cladding layer 215 is doped with a ferrimagnetic or ferromagneticmaterial and is characterized by an appropriate hysteresis curve. Thepreferred embodiment uses a “short” curve that is also “wide” and“flat,” when generating the requisite field. When second cladding layer215 is saturated by a magnetic field generated by an adjacentfield-generating element (e.g., coil 220), itself driven by a signal(e.g., a control pulse) from a controller such as a switching matrixdrive circuit (not shown), second cladding layer 215 quickly reaches adegree of magnetization appropriate to the degree of rotation desiredfor modulator 200. Further, second cladding layer 215 remains magnetizedat or sufficiently near that level until a subsequent pulse eitherincreases (current in the same direction), refreshes (no current or a+/−maintenance current), or reduces (current in the opposite direction)the magnetization level. This remanent flux of doped second claddinglayer 215 maintains an appropriate degree of rotation over time withoutconstant application of a field by influencer 110 (e.g., coil 220).

Appropriate modification/optimization of the doped ferri/ferromagneticmaterial may be further effected by ionic bombardment of the cladding atan appropriate process step. Reference is made to U.S. Pat. No.6,103,010 entitled “METHOD OF DEPOSITING A FERROMAGNETIC FILM ON AWAVEGUIDE AND A MAGNETO-OPTIC COMPONENT COMPRISING A THIN FERROMAGNETICFILM DEPOSITED BY THE METHOD” and assigned to Alcatel of Paris, Francein which ferromagnetic thin-films deposited by vapor-phase methods on awaveguide are bombarded by ionic beams at an angle of incidence thatpulverizes nuclei not ordered in a preferred crystalline structure.Alteration of crystalline structure is a method known to the art, andmay be employed on a doped silica cladding, either in a fabricated fiberor on a doped preform material. The '010 patent is hereby expresslyincorporated by reference for all purposes.

Similar to first cladding layer 210, suitable single-molecule magnets(SMMs) that are developed and which may be magnetized at relative hightemperatures will be preferable as dopants in the preferred embodimentfor second cladding layer 215 to allow for superior dopingconcentrations.

Coil 220 of the preferred embodiment is fabricated integrally on or infiber 200 to generate an initial magnetic field. This magnetic fieldfrom coil 220 rotates the angle of polarization of radiation transmittedthrough core 205 and magnetizes the ferri/ferromagnetic dopant in secondcladding layer 215. A combination of these magnetic fields maintains thedesired angle of rotation for a desired period (such a time of a videoframe when a matrix of fibers 200 collectively form a display asdescribed in one of the related patent applications incorporatedherein). For purposes of the present discussion, a “coilform” is definedas a structure similar to a coil in that a plurality of conductivesegments are disposed parallel to each other and at right-angles to theaxis of the fiber. As materials performance improves—that is, as theeffective Verdet constant of a doped core increases by virtue of dopantsof higher Verdet constant (or as augmented structural modifications,including those introducing non-linear effects)—the need for a coil or“coilform” surrounding the fiber element may be reduced or obviated, andsimpler single bands or Gaussian cylinder structures will be practical.These structures (including the cylinder structures and coils and othersimilar structures), when serving the functions of the coilformdescribed herein, are also included within the definition of coilform.The term coil and coilform may be used interchangeably when the contextpermits.

When considering the variables of the equation specifying the FaradayEffect: field strength, distance over which the field is applied, andthe Verdet constant of the rotating medium, one consequence is thatstructures, components, and/or devices using modulator 200 are able tocompensate for a coil or coilform formed of materials that produce lessintense magnetic fields. Compensation may be achieved by makingmodulator 200 longer, or by further increasing/improving the effectiveVerdet constant. For example, in some implementations, coil 220 uses aconductive material that is a conductive polymer that is less efficientthan a metal wire. In other implementations, coil 220 uses wider butfewer windings than otherwise would be used with a more efficientmaterial. In still other instances, such as when coil 220 is fabricatedby a convenient process but produces coil 220 having a less efficientoperation, other parameters compensate as necessary to achieve suitableoverall operation.

There are tradeoffs between design parameters—fiber length, Verdetconstant of core, and peak field output and efficiency of thefield-generating element. Taking these tradeoffs into considerationproduces four preferred embodiments of an integrally-formed coilform,including: (1) twisted fiber to implement a coil/coilform, (2) fiberwrapped epitaxially with a thin film printed with conductive patterns toachieve multiple layers of windings, (3) printed by dip-pennanolithography on fiber to fabricate a coil/coilform, and (4)coil/coilform wound with coated/doped glass fiber, or alternatively aconductive polymer that is metallically coated or uncoated, or ametallic wire. Further details of these embodiments are described in therelated and incorporated provisional patent application referencedabove.

Node 225 and node 230 receive a signal for inducing generation of therequisite magnetic fields in core 205, cladding layer 215, and coil 220.This signal in a simple embodiment is a DC (direct current) signal ofthe appropriate magnitude and duration to create the desired magneticfields and rotate the polarization angle of the WAVE_IN radiationpropagating through modulator 200. A controller (not shown) may providethis control signal when modulator 200 is used.

Input element 235 and output element 240 are polarization filters in thepreferred embodiment, provided as discrete components or integratedinto/onto core 205. Input element 235, as a polarizer, may beimplemented in many different ways. Various polarization mechanisms maybe employed that permit passage of light of a single polarization type(specific circular or linear) into core 205; the preferred embodimentuses a thin-film deposited epitaxially on an “input” end of core 205. Analternate preferred embodiment uses commercially available nano-scalemicrostructuring techniques on waveguide 200 to achieve polarizationfiltering (such as modification to silica in core 205 or a claddinglayer as described in the incorporated Provisional Patent Application.)In some implementations for efficient input of light from one or morelight source(s), a preferred illumination system may include a cavity toallow repeated reflection of light of the “wrong” initial polarization;thereby all light ultimately resolves into the admitted or “right”polarization. Optionally, especially depending on the distance from theillumination source to modulator 200, polarization-maintainingwaveguides (fibers, semiconductor) may be employed.

Output element 240 of the preferred embodiment is a “polarizationfilter” element that is ninety degrees offset from the orientation ofinput element 235 for a default “off” modulator 200. (In someembodiments, the default may be made “on” by aligning the axes of theinput and output elements. Similarly, other defaults such as fiftypercent amplitude may be implemented by appropriate relationship of theinput and output elements and suitable control from the influencer.)Element 240 is preferably a thin-film deposited epitaxially on an outputend of core 205. Input element 235 and output element 240 may beconfigured differently from the configurations described here usingother polarization filter/control systems. When the radiation propertyto be influenced includes a property other than a radiation polarizationangle (e.g., phase or frequency), other input and output functions areused to properly gate/process/filter the desired property as describedabove to modulate the amplitude of WAVE_OUT responsive to theinfluencer.

FIG. 4 is a schematic block diagram of a preferred embodiment for adisplay assembly 400. Assembly 400 includes an aggregation of aplurality of picture elements (pixels) each generated by a waveguidemodulator 200 _(i,j) such as shown in FIG. 2. Control signals forcontrol of each influencer of modulators 200 _(i,j) are provided by acontroller 405. A radiation source 410 provides source radiation forinput/control by modulators 200 i,j and a front panel may be used toarrange modulators 200 _(i,j) into a desired pattern and or optionallyprovide post-output processing of one or more pixels.

Radiation source 410 may be unitary balanced-white or separate RGB/CMYtuned source or sources or other appropriate radiation frequency.Source(s) 410 may be remote from input ends of modulator 200 _(i,j),adjacent these input ends, or integrated onto/into modulator 200 _(i,j).In some implementations, a single source is used, while otherimplementations may use several or more (and in some cases, one sourceper modulator 200 _(i,j)).

As discussed above, the preferred embodiment for the optical transportof modulator 200 _(i,j) includes light channels in the form of specialoptical fibers. But semiconductor waveguide, waveguiding holes, or otheroptical waveguiding channels, including channels or regions formedthrough material “in depth,” are also encompassed within the scope ofthe present invention. These waveguiding elements are fundamentalimaging structures of the display and incorporate, integrally, amplitudemodulation mechanisms and color selection mechanisms. In the preferredembodiment for an FPD implementation, a length of each of the lightchannels is preferably on the order of about tens of microns (though thelength may be different as described herein).

It is one feature of the preferred embodiment that a length of theoptical transport is short (on the order of about 20 mm and shorter),and able to be continually shortened as the effective Verdet valueincreases and/or the magnetic field strength increases. The actual depthof a display will be a function of the channel length but becauseoptical transport is a waveguide, the path need not be linear from thesource to the output (the path length). In other words, the actual pathmay be bent to provide an even shallower effective depth in someimplementations. The path length, as discussed above, is a function ofthe Verdet constant and the magnetic field strength and while thepreferred embodiment provides for very short path lengths of a fewmillimeters and shorter, longer lengths may be used in someimplementations as well. The necessary length is determined by theinfluencer to achieve the desired degree of influence/control over theinput radiation. In the preferred embodiment for polarized radiation,this control is able to achieve about a ninety degree rotation. In someapplications, when an extinguishing level is higher (e.g., brighter)then less rotation may be used which shortens the necessary path length.Thus, the path length is also influenced by the degree of desiredinfluence on the wave component.

Controller 405 includes a number of alternatives for construction andassembly of a suitable switching system. The preferred implementationincludes not only a point-to-point controller, it also encompasses a“matrix” that structurally combines and holds modulators 200 i,j, andelectronically addresses each pixel. In the case of optical fibers,inherent in the nature of a fiber component is the potential for anall-fiber, textile construction and appropriate addressing of the fiberelements. Flexible meshes or solid matrixes are alternative structures,with attendant assembly methods.

It is one feature of the preferred embodiment that an output end of oneor more modulators 200 _(i,j) may be processed to improve itsapplication. For example, the output ends of the waveguide structures,particularly when implemented as optical fibers, may be heat-treated andpulled to form tapered ends or otherwise abraded, twisted, or shaped forenhanced light scattering at the output ends, thereby improving viewingangle at the display surface. Some and/or all of the modulator outputends may be processed in similar or dissimilar ways to collectivelyproduce a desired output structure achieving the desired result. Forexample, various focus, attenuation, color or other attribute(s) of theWAVE_OUT from one or more pixels may be controlled or affected by theprocessing of one or more output ends/corresponding panel location(s).

Front panel 415 may be simply a sheet of optical glass or othertransparent optical material facing the polarization component or it mayinclude additional functional and structural features. For example,panel 415 may include guides or other structures to arrange output endsof modulators 200 _(i,j) into the desired relative orientation withneighboring modulators 200 _(i,j). FIG. 5 is a view of one arrangementfor output ports 500 _(x,y) of front panel 415 shown in FIG. 4. Otherarrangements are possible are also possible depending upon the desireddisplay (e.g., circular, elliptical or other regular/irregular geometricshape). When an application requires it, the active display area doesnot have to be contiguous pixels such that rings or “doughnut” displaysare possible when appropriate. In other implementations, output portsmay focus, disperse, filter, or perform other type of post-outputprocessing on one or more pixels.

An optical geometry of a display or projector surface may itself vary inwhich waveguide ends terminate to a desired three-dimensional surface(e.g., a curved surface) which allows additional focusing capacity insequence with additional optical elements and lenses (some of which maybe included as part of panel 415). Some applications may requiremultiple areas of concave, flat, and/or convex surface regions, eachwith different curvatures and orientations with the present inventionproviding the appropriate output shape. In some applications, thespecific geometry need not be fixed but may be dynamically alterable tochange shapes/orientations/dimensions as desired. Implementations of thepresent invention may produce various types of haptic display systems aswell.

In projection system implementations, radiation source 410, a “switchingassembly” with controller 405 coupled to modulators 200 _(i,j), andfront panel 415 may benefit from being housed in distinct modules orunits, at some distance from each other. Regarding radiation source 410,in some embodiments it is advantageous to separate the illuminationsource(s) from the switching assembly due to heat produced by the typesof high-amplitude light that is typically required to illuminate a largetheatrical screen. Even when multiple illumination sources are used,distributing the heat output otherwise concentrated in, for instance, asingle Xenon lamp, the heat output may still be large enough that theseparation from the switching and display elements may be desirable. Theillumination source(s) thus would be housed in an insulated case withheat sink and cooling elements. Fibers would then convey the light fromthe separate or unitary source to the switching assembly, and thenprojected onto the screen. The screen may include some features of frontpanel 415 or panel 415 may be used prior to illuminating an appropriatesurface.

The separation of the switching assembly from the projection/displaysurface may have its own advantages. Placing the illumination andswitching assembly in a projection system base (the same would hold truefor an FPD) is able to reduce the depth of a projection TV cabinet. Or,the projection surface may be contained in a compact ball at the top ofa thin lamp-like pole or hanging from the ceiling from a cable, in frontprojection systems employing a reflective fabric screen.

For theatrical projection, the potential to convey the image formed bythe switching assembly, by means of waveguide structures from a unit onthe floor, up to a compact final-optics unit at the projection windowarea, suggests a space-utilization strategy to accommodate both atraditional film projector and a new projector of the preferredembodiment in the same projection room, among other potential advantagesand configurations.

A monolithic construction of waveguide strips, each with multiplethousands of waveguides on a strip, arranged or adhered side by side,may accomplish hi-definition imaging. However, “bulk” fiber opticcomponent construction may also accomplish the requisite smallprojection surface area in the preferred embodiment. Single-mode fibers(especially without the durability performance requirements of externaltelecommunications cable) have a small enough diameter that thecross-sectional area of a fiber is quite small and suitable as a displaypixel or sub-pixel.

In addition, integrated optics manufacturing techniques are expected topermit attenuator arrays of the present invention to be accomplished inthe fabrication of a single semiconductor substrate or chip, massivelymonolithic or superficial.

In a fused-fiber projection surface, the fused-fiber surface may be thenground to achieve a curvature for the purpose of focusing an image intoan optical array; alternatively, fiber-ends that are joined withadhesive or otherwise bound may have shaped tips and may be arranged attheir terminus in a shaped matrix to achieve a curved surface, ifnecessary.

For projection televisions or other non-theatrical projectionapplications, the option of separating the illumination and switchingmodules from the projector surface enables novel ways of achievingless-bulky projection television cabinet construction.

FIG. 6 is a schematic representation of a preferred embodiment of thepresent invention for a portion 600 of the structured waveguide 205shown in FIG. 2. Portion 600 is a radiation propagating channel ofwaveguide 205, typically a guiding channel (e.g., a core for a fiberwaveguide) but may include one or more bounding regions (e.g., claddingsfor the fiber waveguide). Other waveguiding structures have differentspecific mechanisms for enhancing the waveguiding of radiationpropagated along a transmission axis of a channel region of thewaveguide. Waveguides include photonic crystal fibers, special thin-filmstacks of structured materials and other materials. The specificmechanisms of waveguiding may vary from waveguide to waveguide, but thepresent invention may be adapted for use with the different structures.

For purposes of the present invention, the terms guiding region orguiding channel and bounding regions refer to cooperative structures forenhancing radiation propagation along the transmission axis of thechannel. These structures are different from buffers or coatings orpost-manufacture treatments of the waveguide. A principle difference isthat the bounding regions are typically capable of propagating the wavecomponent propagated through the guiding region while the othercomponents of a waveguide do not. For example, in a multimode fiberoptic waveguide, significant energy of higher-order modes is propagatedthrough the bounding regions. One point of distinction is that theguiding region/bounding region(s) are substantially transparent topropagating radiation while the other supporting structures aregenerally substantially opaque.

As described above, influencer 110 works in cooperation with waveguide205 to influence a property of a propagating wave component as it istransmitted along the transmission axis. Portion 600 is therefore saidto have an influencer response attribute, and in the preferredembodiment this attribute is particularly structured to enhance theresponse of the property of the propagating wave to influencer 110.Portion 600 includes a plurality of constituents (e.g., rare-earthdopants 605, holes, 610, structural irregularities 615, microbubbles620, and/or other elements 625) disposed in the guiding region and/orone or more bounding regions as desirable for any specificimplementation. In the preferred embodiment, portion 600 has a veryshort length, in many cases less than about 25 millimeters, and asdescribed above, sometimes significantly shorter than that. Theinfluencer response attribute enhanced by these constituents isoptimized for short length waveguides (for example as contrasted totelecommunications fibers optimized for very long lengths on the orderof kilometers and greater, including attenuation and wavelengthdispersion). The constituents of portion 600, being optimized for adifferent application, could seriously degrade telecommunications use ofthe waveguide. While the presence of the constituents is not intended todegrade telecommunications use, the focus of the preferred embodiment onenhancement of the influencer response attribute over telecommunicationsattribute(s) makes it possible for such degradation to occur and is nota drawback of the preferred embodiment.

The present invention contemplates that there are many different waveproperties that may be influenced by different constructions ofinfluencer 110; the preferred embodiment targets aFaraday-effect-related property of portion 600. As discussed above, theFaraday Effect induces a polarization rotation change responsive to amagnetic field parallel to a propagation direction. In the preferredembodiment, when influencer 110 generates a magnetic field parallel tothe transmission axis, in portion 600 the amount of rotation isdependent upon the strength of the magnetic field, the length of portion600, and the Verdet constant for portion 600. The constituents increasethe responsiveness of portion 600 to this magnetic field, such as byincreasing the effective Verdet constant of portion 600.

One significance of the paradigm shift in waveguide manufacture andcharacteristics by the present invention is that modification ofmanufacturing techniques used to make kilometer-lengths ofoptically-pure telecommunications grade waveguides enables manufactureof inexpensive kilometer-lengths of potentially optically-impure (butoptically-active) influencer-responsive waveguides. As discussed above,some implementations of the preferred embodiment may use a myriad ofvery short lengths of waveguides modified as disclosed herein. Costsavings and other efficiencies/merits are realized by forming thesecollections from short length waveguides created from (e.g., cleaving)the longer manufactured waveguide as described herein. These costsavings and other efficiencies and merits include the advantages ofusing mature manufacturing techniques and equipment that have thepotential to overcome many of the drawbacks of magneto-optic systemsemploying discrete conventionally produced magneto-optic crystals assystem elements. For example, these drawbacks include a high cost ofproduction, a lack of uniformity across a large number of magneto-opticcrystals and a relatively large size of the individual components thatlimits the size of collections of individual components.

The preferred embodiment includes modifications to fiber waveguides andfiber waveguide manufacturing methodologies. At its most general, anoptical fiber is a filament of transparent (at the wavelength ofinterest) dielectric material (typically glass or plastic) and usuallycircular in cross section that guides light. For early optical fibers, acylindrical core was surrounded by, and in intimate contact with, acladding of similar geometry. These optical fibers guided light byproviding the core with slightly greater refractive index than that ofthe cladding layer. Other fiber types provide different guidingmechanisms—one of interest in the context of the present inventionincludes photonic crystal fibers (PCF) as described above.

Silica (silicon dioxide (SiO₂)) is the basic material of which the mostcommon communication-grade optical fibers are made. Silica may occur incrystalline or amorphous form, and occurs naturally in impure forms suchas quartz and sand. The Verdet constant is an optical constant thatdescribes the strength of the Faraday Effect for a particular material.The Verdet constant for most materials, including silica is extremelysmall and is wavelength dependent. It is very strong in substancescontaining paramagnetic ions such as terbium (Tb). High Verdet constantsare found in terbium doped dense flint glasses or in crystals of terbiumgallium garnet (TGG). This material generally has excellent transparencyproperties and is very resistant to laser damage. Although the FaradayEffect is not chromatic (i.e. it doesn't depend on wavelength), theVerdet constant is quite strongly a function of wavelength. At 632.8 nm,the Verdet constant for TGG is reported to be −134 radT−1 whereas at1064 nm, it has fallen to −40radT−1. This behavior means that thedevices manufactured with a certain degree of rotation at onewavelength, will produce much less rotation at longer wavelengths.

The constituents may, in some implements, include an optically-activedopant, such as YIG/Bi—YIG or Tb or TGG or other best-performing dopant,which increases the Verdet constant of the waveguide to achieveefficient Faraday rotation in the presence of an activating magneticfield. Heating or stressing during the fiber manufacturing process asdescribed below may further increase the Verdet constant by addingadditional constituents (e.g., holes or irregularities) in portion 600.Rare-earths as used in conventional waveguides are employed as passiveenhancements of transmission attributes elements, and are not used inoptically-active applications.

Since silica optical fiber is manufactured with high levels of dopantsrelative to the silica percentage itself, as high as at least 50%dopants, and since requisite dopant concentrations have beendemonstrated in silica structures of other kinds to achieve 90° rotationin tens of microns or less; and given improvements in increasing dopantconcentrations (e.g., fibers commercially available from JDS Uniphase)and improvements in controlling dopant profiles (e.g., fibers,commercially available from Corning Incorporated), it is possible toachieve sufficiently high and controlled concentrations ofoptically-active dopant to induce rotation with low power inmicron-scale distances.

FIG. 7 is a schematic block diagram of a representative waveguidemanufacturing system 700 for making a preferred embodiment of awaveguide preform of the present invention. System 700 represents amodified chemical vapor deposition (MCVD) process to produce a glass rodreferred to as the preform. The preform from a conventional process is asolid rod of ultra-pure glass, duplicating the optical properties of adesired fiber exactly, but with linear dimensions scaled-up two ordersof magnitude or more. However, system 700 produces a preform that doesnot emphasize optical purity but optimizes for short-length optimizationof influencer response. Preforms are typically made using one of thefollowing chemical vapor deposition (CVD) methods: 1. Modified ChemicalVapor Deposition (MCVD), 2. Plasma Modified Chemical Vapor Deposition(PMCVD), 3. Plasma Chemical Vapor Deposition (PCVD), 4. Outside VaporDeposition (OVD), 5. Vapor-phase Axial Deposition (AVD). All thesemethods are based on thermal chemical vapor reaction that forms oxides,which are deposited as layers of glass particles called soot, on theoutside of a rotating rod or inside a glass tube. The same chemicalreactions occur in these methods.

Various liquids (e.g., starting materials are solutions of SiCl₄, GeCl₄,POCl₃, and gaseous BCl₃) that provide the source for Si and dopants areheated in the presence in oxygen gas, each liquid in a heated bubbler705 and gas from a source 710. These liquids are evaporated within anoxygen stream controlled by a mass-flow meter 715 and, with the gasses,form silica and other oxides from combustion of the glass-producinghalides in a silica-lathe 720. Chemical reactions called oxidizingreactions occur in the vapor phase, as listed below:GeCl₄+O₂=>GeO₂+2Cl₂SiCl₄+O₂=>SiO₂+2Cl₂4POCl₃+3O₂=>2P2O₅+6Cl₂4BCl₃+3O₂=>2B₂O₃+6Cl₂

Germanium dioxide and phosphorus pentoxide increase the refractive indexof glass, a boron oxide—decreases it. These oxides are known as dopants.Other bubblers 705 including suitable constituents for enhancing theinfluencer response attribute of the preform may be used in addition tothose shown.

Changing composition of the mixture during the process influences arefractive index profile and constituent profile of the preform. Theflow of oxygen is controlled by mixing valves 715, and reactant vapors725 are blown into silica pipe 730 that includes a heated tube 735 whereoxidizing takes places. Chlorine gas 740 is blown out of tube 735, butthe oxide compounds are deposited in the tube in the form of soot 745.Concentrations of iron and copper impurity is reduced from about 10 ppbin the raw liquids to less than 1 ppb in soot 745.

Tube 735 is heated using a traversing H₂O₂ burner 750 and is continuallyrotated to vitrify soot 745 into a glass 755. By adjusting the relativeflow of the various vapors 725, several layers with different indices ofrefraction are obtained, for example core versus cladding or variablecore index profile for GI fibers. After the layering is completed, tube735 is heated and collapsed into a rod with a round, solidcross-section, called the preform rod. In this step it is essential thatcenter of the rod be completely filled with material and not hollow. Thepreform rod is then put into a furnace for drawing, as will be describedin cooperation with FIG. 8.

The main advantage of MCVD is that the reactions and deposition occur ina closed space, so it is harder for undesired impurities to enter. Theindex profile of the fiber is easy to control, and the precisionnecessary for SM fibers can be achieved relatively easily. The equipmentis simple to construct and control. A potentially significant limitationof the method is that the dimensions of the tube essentially limit therod size. Thus, this technique forms fibers typically of 35 km inlength, or 20-40 km at most. In addition, impurities in the silica tube,primarily H₂ and OH—, tend to diffuse into the fiber. Also, the processof melting the deposit to eliminate the hollow center of the preform rodsometimes causes a depression of the index of refraction in the core,which typically renders the fiber unsuitable for telecommunications usebut is not generally of concern in the context of the present invention.In terms of cost and expense, the main disadvantage of the method isthat the deposition rate is relatively slow because it employs indirectheating, that is tube 735 is heated, not the vapors directly, toinitiate the oxidizing reactions and to vitrify the soot. The depositionrate is typically 0.5 to 2 g/min.

A variation of the above-described process makes rare-earth dopedfibers. To make a rare-earth doped fiber, the process starts with arare-earth doped preform—typically fabricated using a solution dopingprocess. Initially, an optical cladding, consisting primarily of fusedsilica, is deposited on an inside of the substrate tube. Core material,which may also contain germanium, is then deposited at a reducedtemperature to form a diffuse and permeable layer known as a ‘frit’.After deposition of the frit, this partially-completed preform is sealedat one end, removed from the lathe and a solution of suitable salts ofthe desired rare-earth dopant (e.g., neodymium, erbium, ytterbium etc.)is introduced. Over a fixed period of time, this solution is left topermeate the frit. After discarding any excess solution, the preform isreturned to the lathe to be dried and consolidated. Duringconsolidation, the interstices within the frit collapse and encapsulatethe rare-earth. Finally, the preform is subjected to a controlledcollapse, at high temperature to form a solid rod of glass—with arare-earth incorporated into the core. Generally inclusion ofrare-earths in fiber cables are not optically-active, that is, respondto electric or magnetic or other perturbation or field to affect acharacteristic of light propagating through the doped medium.Conventional systems are the results of ongoing quests to increase thepercentage of rare-earth dopants driven by a goal to improve “passive”transmission characteristics of waveguides (including telecommunicationsattributes). But the increased percentages of dopants in waveguidecore/boundaries is advantageous for affecting optical-activity of thecompound medium/structure for the preferred embodiment. As discussedabove, in the preferred embodiment the percentage of dopants vs. silicais at least fifty percent.

FIG. 8 is a schematic diagram of a representative fiber drawing system800 for making a preferred embodiment of the present invention from apreform 805, such as one produced from system 700 shown in FIG. 7.System 800 converts preform 805 into a hair-thin filament, typicallyperformed by drawing. Preform 805 is mounted into a feed mechanism 810attached near a top of a tower 815. Mechanism 810 lowers preform 805until a tip enters into a high-purity graphite furnace 820. Pure gassesare injected into the furnace to provide a clean and conductiveatmosphere. In furnace 820, tightly controlled temperatures approaching1900° C. soften the tip of preform 805. Once the softening point of thepreform tip is reached, gravity takes over and allows a molten gob to“free fall” until it has been stretched into a thin strand.

An operator threads this strand of fiber through a laser micrometer 825and a series of processing stations 830 x (e.g., for coatings andbuffers) for producing a transport 835 that is wound onto a spool by atractor 840, and the drawing process begins. The fiber is pulled bytractor 840 situated at the bottom of draw tower 815 and then wound onwinding drums. During the draw, preform 805 is heated at the optimumtemperature to achieve an ideal drawing tension. Draw speeds of 10-20meters per second are not uncommon in the industry.

During the draw process the diameter of the drawn fiber is controlled to125 microns within a tolerance of only 1 micron. Laser-based diametergauge 825 monitors the diameter of the fiber. Gauge 825 samples thediameter of the fiber at rates in excess of 750 times per second. Theactual value of the diameter is compared to the 125 micron target.Slight deviations from the target are converted to changes in drawspeeds and fed to tractor 840 for correction.

Processing stations 830 x typically include dies for applying a twolayer protective coating to the fiber—a soft inner coating and a hardouter coating. This two-part protective jacket provides mechanicalprotection for handling while also protecting a pristine surface of thefiber from harsh environments. These coatings are cured by ultravioletlamps, as part of the same or other processing stations 830 x. Otherstations 830 x may provide apparatus/systems for increasing theinfluencer response attribute of transport 835 as it passes through thestation(s). For example, various mechanical stressors, ion bombardmentor other mechanism for introducing the influencer response attributeenhancing constituents at the drawing stage.

After spooled, the drawn fiber is tested for suitable optical andgeometrical parameters. For transmission fibers, a tensile strength isusually tested first to ensure that a minimal tensile strength for thefiber has been achieved. After the first test, many different tests areperformed, which for transmission fibers includes tests for transmissionattributes, including: attenuation (decrease in signal strength overdistance), bandwidth (information-carrying capacity; an importantmeasurement for multimode fiber), numerical aperture (the measurement ofthe light acceptance angle of a fiber), cut-off wavelength (insingle-mode fiber the wavelength above which only a single modepropagates), mode field diameter (in single-mode fiber the radial widthof the light pulse in the fiber; important for interconnecting), andchromatic dispersion (the spreading of pulses of light due to rays ofdifferent wavelengths traveling at different speeds through the core; insingle-mode fiber this is the limiting factor for information carryingcapacity).

As has been described herein, the preferred embodiment of the presentinvention uses an optic fiber as a transport and primarily implementsamplitude control by use of the “linear” Faraday Effect. While theFaraday Effect is a linear effect in which a polarization rotationalangular change of propagating radiation is directly related to amagnitude of a magnetic field applied in the direction of propagationbased upon the length over which the field is applied and the Verdetconstant of the material through which the radiation is propagated.Materials used in a transport may not, however, have a linear responseto an inducing magnetic field, e.g., such as from an influencer, inestablishing a desired magnetic field strength. In this sense, an actualoutput amplitude of the propagated radiation may be non-linear inresponse to an applied signal from controller and/or influencer magneticfield and/or polarization and/or other attribute or characteristic of amodulator or of WAVE_IN. For purposes of the present discussion,characterization of the modulator (or element thereof) in terms of oneor more system variables is referred to as an attenuation profile of themodulator (or element thereof).

Fiber fabrication processes continue to advance, in particular withreference to improving a doping concentration and as well as improvingmanipulation of dopant profiles, periodic doping of fiber during aproduction run, and related processing activities. U.S. Pat. No.6,532,774, Method of Providing a High Level of Rare Earth Concentrationsin Glass Fiber Preforms, demonstrates improved processes for co-dopingof multiple dopants. Successes in increasing the concentration ofdopants are anticipated to directly improves the linear Verdet constantof doped cores, as well as the performance of doped cores to facilitatenon-linear effects as well.

Any given attenuation profile may be tailored to a particularembodiment, such as for example by controlling a composition,orientation, and/or ordering of a modulator or element thereof. Forexample, changing materials making up transport may change the“influencibility” of the transport or alter the degree to which theinfluencer “influences” any particular propagating wave_component. Thisis but one example of a composition attenuation profile. A modulator ofthe preferred embodiment enables attenuation smoothing in whichdifferent waveguiding channels have different attenuation profiles. Forexample in some implementations having attenuation profiles dependent onpolarization handedness, a modulator may provide a transport for lefthanded polarized wave_components with a different attenuation profilethan the attenuation profile used for the complementary waveguidingchannel of a second transport for right handed polarizedwave_components.

There are additional mechanisms for adjusting attenuation profiles inaddition to the discussion above describing provision of differingmaterial compositions for the transports. In some embodimentswave_component generation/modification may not be strictly “commutative”in response to an order of modulator elements that the propagatingradiation traverses from WAVE_IN to WAVE_OUT. In these instances, it ispossible to alter an attenuation profile by providing a differentordering of the non-commutative elements. This is but one example of aconfiguration attenuation profile. In other embodiments, establishingdiffering “rotational bias” for each waveguiding channel createsdifferent attenuation profiles. As described above, some transports areconfigured with a predefined orientation between an input polarizer andan output polarizer/analyzer. For example, this angle may be zerodegrees (typically defining a “normally ON” channel) or it may be ninetydegrees (typically defining a “normally OFF” channel). Any given channelmay have a different response in various angular displacement regions(that is, from zero to thirty degrees, from thirty to sixty degrees, andfrom sixty to ninety degrees). Different channels may be biased (forexample with default “DC” influencer signals) into differentdisplacement regions with the influencer influencing the propagatingwave_component about this biased rotation. This is but one example of anoperational attenuation profile. Several reasons are present thatsupport having multiple waveguiding channels and totailor/match/complement attenuation profiles for the channels. Thesereasons include power saving, efficiency, and uniformity in WAVE_OUT.

It is a preferred embodiment to implement strategies and factors toreduce power requirements of a continuously-addressed display system.One such strategy is to use a superior Verdet constant of vapor gases byentrapping special vapor gases contained in micro-bubbles withintransport segments. (This embodiment makes use of a linearMacaluso-Corbino effect, i.e., Faraday rotation in the proximity ofabsorption lines. See, for example “Resonant Magneto-Optical Rotation:New Twists in an Old Plot” by Dmitry Budker, et. al., Department ofPhysics, University of California Berkeley, Berkeley, Calif., 4 Jun.2002, the disclosure of which is incorporated by reference in itsentirety for all purposes.)

Implementation of such micro-bubbles may be implemented in conjunctionwith the employment of photonic crystal material (fiber, waveguide,channeled material, and the like). Appropriate quantities and types ofgas vapor is provided within appropriates portions of the waveguidingchannel. Investigating a variant of Faraday rotation in gas vapor (aresonant magneto-optic effect, or “linear Macaluso-Corbino effect”), theresearchers demonstrated an orders-of-magnitude higher Verdet constantin the vapor, as opposed to a solid flint glass reference: Verdetconstant, flint glass: 3×10{circumflex over ( )}−5 Vs. Verdet constant,Resonant rubidium vapor: 10{circumflex over ( )}4.

Budker et al concluded that the effective improvement in Verdet constant(“per atom”), between the use of transparent, optically-active solids,and a gas vapor, (taking into account the difference in density), is onthe order of 10{circumflex over ( )}20. Implementation of gas vapor inhollow, partial vacuum fiber (standard or photonic crystal), or sealedchannels in photonic crystal would then reduce the required magneticfield strength per unit length (or reduce the length for a givenmagnetic field strength) or a combination of both.

Considering again the formula for Faraday rotation given above (Eq. (1)above), then an increase in effective Verdet constant from3×10{circumflex over ( )}−5 to 10{circumflex over ( )}4 means areduction in the required length “I” and/or the required field or fluxintensity, by a combined factor of, conservatively, 10{circumflex over( )}−8. Thus, implementation of gas vapor as the rotating medium is ableto reduce, for instance, the input current range to rotate 0-90 degreesfrom 0-50 milliamps to 0-5 microamps, (10{circumflex over ( )}6 amps)and required length of rotator element from mm's or tens of microns, tofractions of microns.

In the preferred embodiment, this implementation provides fibers thatare doped with gas bubbles, as in the case of standard fiber that isdoped and later heat-treated by established means to form holes, therebyresulting in a cost-effectively manufactured PCF (photonic crystalfiber). Properly doped, rarified vapor gases are found in the resultantholes will enhance the overall Verdet constant of the transport.Optionally, gas bubbles may be introduced in the fiber perform stage bypressure injection and methods known and established in glassfabrication.

Implementation of a vapor for pumping and resonant cavities is thusachieved by introduction of micro-bubbles or cavities. This may beaccomplished, for example, by the heat-treatment processes referencedelsewhere herein and in the incorporated patent applications, which incombination with addition of alkali dopant, may leach sufficient alkalimolecules to result in a rarified alkali vapor in the micro-bubbles. Or,micro-bubbles may be introduced and unsuppressed at the preform stage,as disclosed elsewhere herein.

Statistical analysis can determine the power demand profile of a FLATactive-matrix/continuously-addressed device due to these considerations.It is, in any event, significantly less than an imaginary maximum ofeach sub-pixel of the display simultaneously at full Faraday rotation.By no means are all sub-pixels “on” for any given frame, and intensitiesfor those “on” are, for various reasons, typically at some relativelysmall fraction of maximum. Regarding current requirements, 0-50 m.ampsfor 0-90° Rotation is considered a Minimum Spec It is also important tonote that an example current range for 0-90° rotation has been given(0-50 m.amps) from performance specs of existing Faraday attenuatordevices, but this performance spec is provided as a minimum, alreadyclearly being superseded and surpassed by the state-of-the-art ofreference devices for optical communications. It most importantly doesnot reflect the novel embodiments specified in the present invention,including the benefits from improved methods and materials technology.Performance improvements have been ongoing since the achievement of thespecs cited, and if anything have been and will continue to beaccelerating, further reducing this range.

The system, method, computer program product, and propagated signaldescribed in this application may, of course, be embodied in hardware;e.g., within or coupled to a Central Processing Unit (“CPU”),microprocessor, microcontroller, System on Chip (“SOC”), or any otherprogrammable device. Additionally, the system, method, computer programproduct, and propagated signal may be embodied in software (e.g.,computer readable code, program code, instructions and/or data disposedin any form, such as source, object or machine language) disposed, forexample, in a computer usable (e.g., readable) medium configured tostore the software. Such software enables the function, fabrication,modeling, simulation, description and/or testing of the apparatus andprocesses described herein. For example, this can be accomplishedthrough the use of general programming languages (e.g., C, C++), GDSIIdatabases, hardware description languages (HDL) including Verilog HDL,VHDL, AHDL (Altera HDL) and so on, or other available programs,databases, nanoprocessing, and/or circuit (i.e., schematic) capturetools. Such software can be disposed in any known computer usable mediumincluding semiconductor, magnetic disk, optical disc (e.g., CD-ROM,DVD-ROM, etc.) and as a computer data signal embodied in a computerusable (e.g., readable) transmission medium (e.g., carrier wave or anyother medium including digital, optical, or analog-based medium). Assuch, the software can be transmitted over communication networksincluding the Internet and intranets. A system, method, computer programproduct, and propagated signal embodied in software may be included in asemiconductor intellectual property core (e.g., embodied in HDL) andtransformed to hardware in the production of integrated circuits.Additionally, a system, method, computer program product, and propagatedsignal as described herein may be embodied as a combination of hardwareand software.

One of the preferred implementations of the present invention, forexample for the switching control, is as a routine in an operatingsystem made up of programming steps or instructions resident in a memoryof a computing system during computer operations. Until required by thecomputer system, the program instructions may be stored in anotherreadable medium, e.g. in a disk drive, or in a removable memory, such asan optical disk for use in a CD ROM computer input or in a floppy diskfor use in a floppy disk drive computer input. Further, the programinstructions may be stored in the memory of another computer prior touse in the system of the present invention and transmitted over a LAN ora WAN, such as the Internet, when required by the user of the presentinvention. One skilled in the art should appreciate that the processescontrolling the present invention are capable of being distributed inthe form of computer readable media in a variety of forms.

Any suitable programming language can be used to implement the routinesof the present invention including C, C++, Java, assembly language, etc.Different programming techniques can be employed such as procedural orobject oriented. The routines can execute on a single processing deviceor multiple processors. Although the steps, operations or computationsmay be presented in a specific order, this order may be changed indifferent embodiments. In some embodiments, multiple steps shown assequential in this specification can be performed at the same time. Thesequence of operations described herein can be interrupted, suspended,or otherwise controlled by another process, such as an operating system,kernel, etc. The routines can operate in an operating system environmentor as stand-alone routines occupying all, or a substantial part, of thesystem processing.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the present invention. One skilled inthe relevant art will recognize, however, that an embodiment of theinvention can be practiced without one or more of the specific details,or with other apparatus, systems, assemblies, methods, components,materials, parts, and/or the like. In other instances, well-knownstructures, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of thepresent invention.

A “computer-readable medium” for purposes of embodiments of the presentinvention may be any medium that can contain, store, communicate,propagate, or transport the program for use by or in connection with theinstruction execution system, apparatus, system or device. The computerreadable medium can be, by way of example only but not by limitation, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, system, device, propagation medium, orcomputer memory.

A “processor” or “process” includes any human, hardware and/or softwaresystem, mechanism or component that processes data, signals or otherinformation. A processor can include a system with a general-purposecentral processing unit, multiple processing units, dedicated circuitryfor achieving functionality, or other systems. Processing need not belimited to a geographic location, or have temporal limitations. Forexample, a processor can perform its functions in “real time,”“offline,” in a “batch mode,” etc. Portions of processing can beperformed at different times and at different locations, by different(or the same) processing systems.

Reference throughout this specification to “one embodiment”, “anembodiment”, “a preferred embodiment” or “a specific embodiment” meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe present invention and not necessarily in all embodiments. Thus,respective appearances of the phrases “in one embodiment”, “in anembodiment”, or “in a specific embodiment” in various places throughoutthis specification are not necessarily referring to the same embodiment.Furthermore, the particular features, structures, or characteristics ofany specific embodiment of the present invention may be combined in anysuitable manner with one or more other embodiments. It is to beunderstood that other variations and modifications of the embodiments ofthe present invention described and illustrated herein are possible inlight of the teachings herein and are to be considered as part of thespirit and scope of the present invention.

Embodiments of the invention may be implemented by using a programmedgeneral purpose digital computer, by using application specificintegrated circuits, programmable logic devices, field programmable gatearrays, optical, chemical, biological, quantum or nanoengineeredsystems, components and mechanisms may be used. In general, thefunctions of the present invention can be achieved by any means as isknown in the art. Distributed, or networked systems, components andcircuits can be used. Communication, or transfer, of data may be wired,wireless, or by any other means.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application. It isalso within the spirit and scope of the present invention to implement aprogram or code that can be stored in a machine-readable medium topermit a computer to perform any of the methods described above.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Furthermore, the term “or” as used herein isgenerally intended to mean “and/or” unless otherwise indicated.Combinations of components or steps will also be considered as beingnoted, where terminology is foreseen as rendering the ability toseparate or combine is unclear.

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the Abstract, is not intendedto be exhaustive or to limit the invention to the precise formsdisclosed herein. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope of thepresent invention, as those skilled in the relevant art will recognizeand appreciate. As indicated, these modifications may be made to thepresent invention in light of the foregoing description of illustratedembodiments of the present invention and are to be included within thespirit and scope of the present invention.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of embodiments of the invention will be employed without acorresponding use of other features without departing from the scope andspirit of the invention as set forth. Therefore, many modifications maybe made to adapt a particular situation or material to the essentialscope and spirit of the present invention. It is intended that theinvention not be limited to the particular terms used in followingclaims and/or to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include any and all embodiments and equivalents falling within thescope of the appended claims. Therefore the scope of the invention is tobe determined solely by the appended claims.

1. A transport, comprising: a waveguide including a guiding region andone or more bounding regions for enhancing containment of transmittedradiation within said guiding region, a portion of said waveguidedefining a plurality of voids; and a gas disposed in said plurality ofvoids to enhance an influencer response attribute of said waveguide. 2.The transport of claim 1 wherein said waveguide is a photonic crystalfiber.
 3. The transport of claim 1 wherein said influencer responseattribute includes a polarization angle rate of change responsive to animposed magnetic.
 4. The transport of claim 1 wherein said influencerresponse attribute includes a Verdet constant of said waveguide.
 5. Atransport manufacturing method, the method comprising: a) forming awaveguide having a guiding region and one or more bounding regions forenhancing containment of transmitted radiation within said guidingregion, a portion of said waveguide defining a plurality of voids; andb) disposing a gas in said plurality of voids to enhance an influencerresponse attribute of said waveguide.
 6. The manufacturing method ofclaim 5 wherein said disposing step b) is injected.
 7. The manufacturingmethod of claim 5 wherein said disposing step b) includes doping saidwaveguide with said gas and treating said waveguide to produce saidplurality of voids having said gas disposed therein.
 8. A method ofoperating a transport, comprising: a) propagating a radiation signalthrough a waveguide including a guiding region and one or more boundingregions for enhancing containment of transmitted radiation within saidguiding region, a portion of said waveguide defining a plurality ofvoids; and b) enhancing a response of said radiation signal to aninfluencer applying an influence on said waveguide using a gas disposedin said plurality of voids.
 9. A propagated signal on which is carriedcomputer-executable instructions which when executed by a computingsystem performs a method, the method comprising: a) forming a waveguidehaving a guiding region and one or more bounding regions for enhancingcontainment of transmitted radiation within said guiding region, aportion of said waveguide defining a plurality of voids; and b)disposing a gas in said plurality of voids to enhance an influencerresponse attribute of said waveguide.
 10. A computer program productcomprising a computer readable medium carrying program instructions formanufacturing a transport when executed using a computing system, theexecuted program instructions executing a method, the method comprising:a) propagating a radiation signal through a waveguide including aguiding region and one or more bounding regions for enhancingcontainment of transmitted radiation within said guiding region, aportion of said waveguide defining a plurality of voids; and b)enhancing a response of said radiation signal to an influencer applyingan influence on said waveguide using a gas disposed in said plurality ofvoids.